Devices for expanding an elastic band so that the band may be placed around an object have long been used. Various applications of such devices include animal castration, application of O-rings to machine parts, application of closing bands to sacks or bags, the application of sealing bands to hose fittings and the like, and the collaring of various materials to hold them together.
One example of an elastic band expander is the device of U.S. Pat. No. 3,600,788 to Armand, which provides a tool for castrating animals. The Armand tool includes two handles, one to be activated by either hand, which operate to stretch a rubber band around a cylindrical sleeve. The Armand device requires the use of both hands at all times during the operation to stretch and hold the rubber band open. While this is effective for the intended purpose of the invention, other applications of an elastic band expander would be better served by a device that could be operated with a single hand, and which had the capability of locking in the open position in order to allow better placement of the article to be collared. U.S. Pat. No. 3,281,927 to Buslaff provides a tool for dilating elastic rings and tubes, particularly for use in the manufacture of teat cups for milking machines. The Buslaff tool also provides handles, which activate a set of lever arms to stretch an elastic band. However, like the Armand tool, the Buslaff tool does not provide any locking capability for holding the elastic band in an open position without requiring continuous hand pressure by the operator.
U.S. Pat. No. 2,601,547 to Minock provides a tool directed primarily at animal castration. Minock utilizes a set of expanding elements which have pins riding in cam slots. Handles are used to cause the pins to move outward in the cam slots, thereby moving the expanding elements outward and expanding the elastic band. However, the Minock device also suffers from the lack of any locking capability. Minock's later U.S. Pat. No. 2,700,387 recognizes this shortcoming, and provides a spring-loaded locking pin for holding the device in an open position. However, the operator of Minock's '387 device must first choose whether or not to engage the locking function of the pin. Once the locking function is engaged, a spring will force the locking pin into a hole when the device is fully opened, thereby locking the device in the open position. In order to unlock the device, the operator must perform the additional step of manually removing the locking pin from the hole, overcoming the pressure from the spring. While this approach to locking and unlocking the device is functional, a device requiring fewer parts and fewer steps in the locking and unlocking process would be desirable.
Additionally, various tools have been used commercially for expanding elastic band in order to collar skirts for fishing lures. Typical of such devices is one which is very similar in appearance to a set of needle-nose pliers, but which operates in reverse fashion. That is, an elastic band is placed over the needle-nose prongs of the device, and the handles are then activated, causing the device to open rather than to close, as would be the case with needle-nose pliers. Like other band expanders for fishing lure skirts, such needle-nose devices generally suffer from stretching the elastic band in only a linear direction. This results in a mere slit in the elastic band, through which it is quite difficult to position material to be collared. One such needle-nose expander provides a bar which may be fixed at either of its ends to one handle of the device, and at its other end to the other handle of the device, to hold the device in the open position. The bar must then be removed to allow the device to close. While this approach is effective in locking the device in an open position, it requires additional parts and steps, and is awkward to use in practice.
There is thus a need for an elastic band expander which requires a minimum of effort to operate, and which expands an elastic band in more than a linear direction, in order to provide a sufficiently large opening in the band to facilitate the collaring operation. Further, there is a need for an expander which will easily lock into an open position, which may be quickly and easily unlocked, and which may generally be operated in such a way as to free the user's hands for other tasks.